Seems how other unqualified individuals have chimed in and seem to disregard the statements of qualified individuals I figure I can chime back in.
Being on trial indicates that the use of a firearm was not so simplistic as to be simply accepted as being self defense or some other legal use. I suppose, an even worse case scenario, is that it is politically motivated and the prosecutor is trying for a political conviction without regards to the actual facts.
The original poster asked about evidentiary concerns. My mistake in my original replies as I am most interested in (but no qualified to give legal advise) on jury deliberations and how evidence may impact a jury (see the Harold Fish) case.
A "standard" load created, marketed, and produced by a neutral third party is not likely, in my unqualified opinion, to present remarkable evidentiary concerns. The two concerns are: does the evidence produced support the chain of events as told by the defendant and if the evidence does not why does it not. For the purpose of this discussion I am going to assume the defendant's memory is accurate and the his or her telling of the chain of events is truthful - obviously both of these things are in question in a non-theoretical discussion.
If the evidence does support the chain of events as told by the defendant then everything is wonderful. In this case the prosecution is not likely to bring it up and, as the defendant is not likely to testify, it is not likely to be part of the defense. The prosecution, in seeing exactly how a particular brand of ammo functions in regards to a particular test is likely to purchase some of that ammo off the shelf and test the results against it. Everything lines up you are good to go.
What if it doesn't line up? This is where you, as a defendant, have a clear advantage over hand-loaded ammunition. Why do you recollect the shooting happening at a couple yards while the prosecution finds evidence, such as gun shot residue, that shows it occurring at a much longer range. You at this point are going to be left questioning the manufacturing process. You're team can pull a few hundred rounds and start testing for consistency - an inconsistency would throw off the test results and throw off the evidence introduced by the prosecutor.
Frankly I am not certain how a database of evidentiary material would help you. It is unlikely the prosecution is going to use round specific evidence to clear you and its unlikely your defense is going to find such detailed forensic information to be central to your case if things have gone that badly for you. In a justified shooting defense you are basically only trying to maintain your version of the events as simply as possible. Evidence introduced to be used against you will need to be called into question or obscured some how but I don't see that being an issue with commonly manufactured "boutique" ammunition that your defense will be readily able to purchase.